Improvement in lifting-jacks



A. S. DINSMORE.

Lifting-Jack. No. 211,891. Patented Feb. 4,1879.

WHILE 5 5,2 '5 Ir Eq 1:131".

N- PETERS, PHOTO-UTHOGRAPNEH. WASHI UNITED STATES PATENT UEEToE.

ALFRED S. DINSMORE, OF BOSTON, ASSIGNOR OF ONE-HALF HIS RIGHT TO CHAS.F. OURWEN, OF SALEM, MASSACHUSETTS.

IMPROVEMENT IN LlFTlNG-JACKS.

Specification forming part of Letters Patent No. 211,891; dated February4, 1879 application filed October 25, 1878.

To all whom "it may concern:

Be it known that I, ALFRED S. DINSMORE, of Boston, county of Suffolk,State of Massachusetts, have invented an Improvement in Lifting-Jacks,of which the following description, in connection with the accompanyingdrawing, is a specification.

This invention relates to lifting-jacks, and has for its object theproduction of a cheap and easily-operated jack.

The invention consists in an improved jack composed of an internallyscrewthreaded bottom standard, an externally-threaded rod, a fulcrumfixed upon the rod, a lifting-lever pivoted thereon, and a head and aguide connected therewith to co-operate with the upper end of the saidrod, the sleeve being connected with the lever by means of links, substantially as hereinafter shown and described.

The drawing represents, in side elevation, a jack constructed inaccordance with my invention, the head being shownin full lines aselevated, and in dotted lines as lowered.

The standard a, having a base portion, 0, is internally screw-threadedto receive within it the externally-threaded rod 0, the upper end ofwhich, as at (I, is left smooth to receive the guide or sleeve 0,provided at its upper end with the head f. This guide 6 will preferablybe cast with the head and with a side rest, 9,

having one or more notches or shoulders, 2

A sleeve arranged outside the rod 0 may be easily provided at its outerside with side rests close to the line of movement of the guide orsleeve, rather than at a considerable distance therefrom, as in UnitedStates Patent No. 202,197 5 and the said rests consequently in no wayinterfere with the vertical movement of the sleeve.

The fulcrum i for the lever j is shown as a collar fixed upon the rod 0,the collar being provided with an ear to receive the pin 4, upon whichthe lever j turns.

To raise and lower the head f the proper distance, according to theheight of the article to be lifted, the rod may be rotated in thestandard by means of the handle.

The links it connect the forked ends of the lever j with the portion ef.

By making the fulcrum i a fixture with relation to theexternally-threaded rod 0, it is obvious that the guide, fitted to riseand fall with relation to the upper end of the said rod under the actionof the lever, is always made to 00- cupy the same position withreference to the end of the rod 0, no matter what may be the change ofposition of the rod with relation to the standard a, whereby the strainupon the guide is always the same under all adjustments of the jack,which is not the case when the lever for lifting the guide is mountedupon a nut which is movable vertically along the standard, as in thepatent referred to.

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